title: Low expression of the X-linked ribosomal protein S4 in human serous epithelial ovarian cancer is associated with a poor prognosis.
abstract: BACKGROUND
  The X-linked ribosomal protein S4 (RPS4X), which is involved in cellular translation and proliferation, has previously been identified as a partner of the overexpressed multifunctional protein YB-1 in several breast cancer cells. Depletion of RPS4X results in consistent resistance to cisplatin in such cell lines.
  
  
  METHODS
  As platinum-based chemotherapy is a standard first line therapy used to treat patients with ovarian cancer, we evaluated the prognostic value of RPS4X and YB-1 at the protein level in specimen from 192 high-grade serous epithelial ovarian cancer patients.
  
  
  RESULTS
  Immunohistochemistry studies indicated that high expression of RPS4X was associated with a lower risk of death and later disease progression (HR = 0.713, P = 0.001 and HR = 0.761, P = 0.001, respectively) as compared to low expression of RPS4X. In contrast, YB-1 was not significantly associated with either recurrence or survival time in this cohort. Finally, the depletion of RPS4X with different siRNAs in two different ovarian cancer cell lines reduced their proliferative growth rate but more importantly increased their resistance to cisplatin.
  
  
  CONCLUSIONS
  Altogether, these results suggest that the levels of RPS4X could be a good indicator for resistance to platinum-based therapy and a prognostic marker for ovarian cancer. Our study also showed that RPS4X is an independent prognostic factor in patients with serous epithelial ovarian cancer.
authors.affiliation: Centre de Recherche en Cancérologie de l'Université Laval, Hôpital Hôtel-Dieu de Québec, Quebec City, QC, Canada.
authors.forename: Serges P
authors.initials: SP
authors.lastname: Tsofack
authors.forename: Liliane
authors.initials: L
authors.lastname: Meunier
authors.forename: Lilia
authors.initials: L
authors.lastname: Sanchez
authors.forename: Jason
authors.initials: J
authors.lastname: Madore
authors.forename: Diane
authors.initials: D
authors.lastname: Provencher
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Mes-Masson
authors.forename: Michel
authors.initials: M
authors.lastname: Lebel
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D015153:Blotting, Western; D000077216:Carcinoma, Ovarian Epithelial; D018284:Cystadenocarcinoma, Serous / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality; D019008:Drug Resistance, Neoplasm / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality; D011379:Prognosis; D016016:Proportional Hazards Models; D012269:Ribosomal Proteins / Q000032:analysis / Q000096:biosynthesis*; D046888:Tissue Array Analysis; D014162:Transfection; D051840:Y-Box-Binding Protein 1 / Q000032:analysis / Q000096:biosynthesis
chemical_list: D014408:Biomarkers, Tumor; D012269:Ribosomal Proteins; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; C031798:ribosomal protein S4